So far so good! So far I've used a few of these to spread the steering knuckles apart to remove the ball joint studs, drive out the pins and bolts and remove the stubborn brake rotor bolts. They were not covered with mushrooms at all and did not break. Only complaint is the crappy little tray it comes in. It's nice because it's in a small form factor, but damn they were hard to pull out without breaking. The transparent cover on the front is placed in the middle of the small dividers between the different types and it's almost impossible to remove if you want to keep the tablet intact. I ended up drilling out the spots where it was attached so the tray could be used.